Abstract: The system provides for vertical or horizontal centering, or both, without the use of a memory frame buffer, of raster image data whose start time and duration cannot be controlled. The centering is accomplished by controlling the frame start time and line start time of the overall display of the raster imaging surface. This is accomplished in the case of vertical centering by detecting the time of the beginning of the first or last line, or both, of the total lines of the raster image data to be displayed an controlling the start time of a subsequent one of the frames based on that detected time. Horizontal centering is carried out by detecting the time of the beginning of the first or last column, or both, of the columns in one or more of the lines of the raster image data and controlling the start time of subsequent ones of the lines based on that detected time.

Abstract: A method and apparatus for increasing the perceived gradation of the shades in visual displays is disclosed. A plurality of signals control the intensity of a sub-pixel of a display so that display can exhibit a native number of shades. Frame rate modulation techniques are used to increase the perceived gradation. Finally, flicker is reduced by spreading the phases of the modulating pixels across time, and the horizontal and vertical axes of the display.

Abstract: An apparatus is disclosed for controlling primary color producing sub-pixels of a digitally commanded display to provide mixed colors in which sub-pixels are controlled over a programmable number N of consecutive frames to be either ON or OFF during each of the frames so that a desired time averaged brightness is produced of the primary color associated with each sub-pixel, and so that the combination of the produced time averaged brightnesss results in the color desired for the pixel to which the sub-pixels belong. The apparatus employs a modulo-N adder for programmably controlling each primary color sub-pixel by using a frame rate duty cycle approach.

Abstract: The perception of grayscale shading on a digitally commanded display is produced by commanding pixels of the display with brightness-setting signals of differing average duty cycles. Brightness-setting signals having one brightness level associated with them are phase shifted in relation to time and distributed to spaced apart pixel locations at which the one brightness level is to be produced. The energization of spatially adjacent pixels is scattered in time and pixels which are energized at the same time are selected to be spatially scattered so as to avoid the perception of visual disturbances such as flickering and surface streaming.

Abstract: The system provides for vertical or horizontal centering, or both, without the use of a memory frame buffer, of raster image data whose start time and duration cannot be controlled. The centering is accomplished by controlling the frame start time and line start time of the overall display of the raster imaging surface. This is accomplished in the case of vertical centering by detecting the time of the beginning of the first or last line, or both, of the total lines of the raster image data to be displayed and controlling the start time of a subsequent one of the frames based on that detected time. Horizontal centering is carried out by detecting the time of the beginning of the first or last column, or both, of the columns in one or more of the lines of the raster image data and controlling the start time of subsequent ones of the lines based on that detected time.

Abstract: The perception of grayscale shading on a digitally commanded display is produced by commanding pixels of the display with brightness-setting signals of differing average duty cycles. Brightness-setting signals having one brightness level associated with them are phase shifted in relation to time and distributed to spaced apart pixel locations at which the one brightness level is to be produced. The energization of spatially adjacent pixels is scattered in time and pixels which are energized at the same time are selected to be spatially scattered so as to avoid the perception of visual disturbances such as flickering and surface streaming.

Abstract: A frame rate duty cycle technique and dithering technique is applied to the output of a color look-up RAM in order to drive various flat panel displays. An integrated circuit chip in accordance with the invention includes a modulo-N gray scaling unit, where the value N is variable as well as a pixels dithering unit and a color mixing unit. A brightness spreading memory is included for mapping CRT drive values into LCD drive values.